The Long Term Evolution-Advanced (LTE-A) currently under standardization by the 3rd Generation Partnership Project GPP) defines a heterogeneous network (HetNet), which is an overlay network using various types of cells with different transmission power levels, such as picocells, femtocells, remote radio heads (RRHs) besides conventional macrocells (see Non-patent Document 1, for example).
The heterogeneous network prescribes application of cell range expansion in which a cell radius of a picocell or the like is expanded by applying a bias to reception quality (received power) used in cell selection by a mobile station. Thus, when a macrocell is overlaid on a picocell or the like, it is possible to offload more traffic from the macrocell to the picocell.
A mobile station handed over to the picocell as a result of application of the bias receives large interference from the macrocell because the mobile station is situated in an environment usually well connectable to the macrocell. This is why enhanced inter-cell interference coordination (eICIC) is necessary. Specifically, there is known inter-cell interference coordination to avoid interference by causing a macrocell and a picocell to use different radio resources in a time domain or a frequency domain.
For example, in the inter-cell interference coordination in the time domain, radio resource blocks in the time domain for the macrocell to transmit a radio signal are determined by an almost blank subframe (ABS) pattern which controls the time domain to be allocated to the macrocell.